The present application hereby claims priority under 35 U.S.C. xc2xa7119 on German patent publication number DE 10144106.1 filed Sep. 3, 2001, the entire contents of which are hereby incorporated by reference.
The invention generally relates to an electrical circuit breaker having a detachable connection between a switching contact arrangement and a actuating shaft which operates it. Preferably, the switching contact arrangement is held between two housing bodies, which can be separated from one another, of the circuit breaker. Furthermore, a coupling bolt, which is preferably held in a contact support of the switching contact arrangement, preferably engages in a lever arrangement, which is connected to the actuating shaft.
Circuit breakers are described, for example, in DE 196 37 678 A1, DE 296 08 061 U1 or EP 0 225 207 B1. Circuit breakers are designed for a long life, by virtue of their use in power supply systems and by virtue of the requirements for high reliability that exist here. For example, loading with high switching ratings, for example when interrupting short-circuit currents, does not lead to the entire circuit breaker, but only to specific components, being completely worn out or becoming unusable. These include, in particular, all the components of the switching contact arrangements, since these are subject directly to the high energy of switching arcs, whose influence results in the contact material being worn away or being lost. The detachable connection between the switching contact arrangements and the drive apparatus which operates it allows only the worn-away switching contact arrangement to be replaced, while all the other components in the circuit breaker can still be used.
The detachable connection which has been mentioned between the switching contact arrangement and the associated drive apparatus is generally designed such that a coupling bolt is arranged in a movable contact support in the switching contact arrangement, and connects the contact support in a hinged manner to the lever arrangement which has been mentioned. Suitable configuration of the contact support and/or of the coupling bolt allows the coupling bolt to be moved or to be removed using commercially available tools, once they have been made accessible, for example by removing arcing chambers or other parts of the circuit breaker that cover the switching contact arrangement.
Once the housing bodies have been disconnected, the switching contact arrangement can then be removed completely, so that all the live parts of the main current path in the circuit breaker are accessible. These are, firstly, a lower busbar, which is generally connected to one or more movable contact levers via flexible conductors which cannot be disconnected, and whose end which projects to the rear out of the housing body forms an external connection for the circuit breaker. There is also an upper busbar, which interacts with the contact levers and in the same way forms a connection for the circuit breaker.
When these parts are replaced, the connection for the lever arrangement must then be made once again. This requires the lever arrangement to be in a specific position, which in turns depends on the position of the actuating shaft. However, for its part, this cannot be rotated without any restrictions, since it is connected to latching parts of the drive apparatus. This leads to the difficulty that the actuating shaft may be located in the ON position after the switching contact arrangement has been replaced, so that the rearward housing body of the circuit breaker, through which the busbars extend, cannot be connected to the associated front housing body without exerting force. This is because this would necessitate applying a load to all the contact force springs of the switching contact arrangements (depending on the configuration of the circuit breaker 3 or 4).
Since this is impractical, the only possible option is to move the actuating shaft to its disconnected position. To do this, it is necessary to operate latching parts, which are located in the drive apparatus by hand and to move further mechanical elements temporarily to a specific position. One precondition for this is that access is first of all created to the relevant assemblies of the drive apparatus by removing a number of assemblies from the circuit breaker. This work is time-consuming and requires detailed knowledge about the design of the relevant circuit breaker. Thus, in general, switching contact arrangements can be replaced only by specially trained specialists in a special workshop.
An embodiment of the invention is based on an object of considerably simplifying the replacement of a switching contact arrangement and, in particular, of restricting this to steps which can also be carried out by the user of the circuit breaker.
According to an embodiment of the invention, an object may be achieved in that a holding piece is provided for fixing the actuating shaft in a position which is suitable for disconnection and for renewed connection to the contact support. If the angular position of the actuating shaft is chosen in a suitable manner, this allows operation without application of any force, and without any manipulation of or actions on the latching devices of the drive apparatus. Since, furthermore, no access is required to the drive apparatus either, there is no need for the previously required steps of removing and reinstalling assemblies which are adjacent to the drive apparatus.
For the purposes of an embodiment of the invention, it has been found to be advantageous for the holding piece to be in the form of a handle lever and to have a coupling member for rotationally locked coupling to the actuating shaft. In this embodiment the holding piece can be used easily by the user, provided the actuating shaft of the circuit breaker is designed in a known manner such that it can itself be coupled. One example of this is illustrated in FIG. 5 of EP 0 789 925 B1.
If, at the same time, it can be assumed that there is no need to exert a large amount of force to move the actuating shaft to the position which is suitable for replacement of switching contact arrangement, it is recommended that the holding piece be provided with a handle part, which is used to exert a torque on the actuating shaft; and it is recommended that an aperture opening be provided, which passes through the handle part, for holding an attachment means which fixes the holding piece in an end position.
The handle part with the aperture opening can advantageously be used in particular in a circuit breaker which has a control panel which covers the front of the drive apparatus and can be detachably attached to a front housing body. This is because the contact surface and holding openings for an attachment device for the control panel are accessible once the control panel has been removed from the circuit breaker. If the holding piece is now designed such that, in its end position, its handle part rests on a contact surface, which is provided for the control panel, on the front housing body and the aperture opening corresponds to a holding opening, which is located on the contact surface, for the attachment device for the control panel, then the user can easily fix the holding piece.
If any or all of the configurations described above are implemented, then these allow a procedure sequence for replacement of a switching contact arrangement which is advantageously shorter than that for the previous procedures:
a) removal of the control panel of the circuit breaker,
b) fitting of the holding piece to the actuating shaft and rotation of the actuating shaft to a predetermined end position,
c) attachment of the holding piece for maintaining the end position,
d) releasing the attachment means in order to disconnect the housing bodies which hold the switching contact arrangement,
e) releasing the connection between the contact support and the lever arrangement,
f) removal of the switching contact arrangement and insertion of another switching contact arrangement,
g) making the connection between the lever arrangement and the contact support,
h) joining the housing bodies and insertion of the associated attachment means,
i) removal of the holding piece,
k) fitting of the control panel.